Applications And Features - Honeywell HON 985A Manual

1.3

Applications and features

• Application
– Variable mixing of air and fuel gas for gas engines (e.g. for λ-control, electronic spark control,
combustion-chamber temperature control)
– Mixing gases for operating gas motors with multiple types of fuel gas (e.g. sewage gas, secondary operation
with natural gas)
– In general, mixing all sorts of gases (e.g. boosting low calorific-value gases e.g. waste dump gas)
– Applicable for natural gas, sewage gas, dump gas, mine gas, propane, butane and neutral gases
• Features
– Simple construction
– Adjustable fuel-gas mixing gap provides for flexible mixing ratios
– Fine adjustment of mixing ratios possible
– Sensitive stepper motors provide for precise adjustment of mixing gap
– Turbulent mixing (homogenization)
1.4 Structure and mode of operation
gas 2 (fuel gas) flowing in through an upstream gas pressure control section to the same pressure as gas 1 (air). With the
reduction of the cross-section, there is an acceleration of gas 1 (air) flowing in. Acceleration means the pressure of the gas
For the mixture of the gases, a torpedo designed for maximum flow rates of the gas mixture is integrated in the device.
The downstream flow edges of the torpedo support the turbulent mixing of the two types of gases (homogenization).
For a more precise adjustment of the mixing ratio (λ-control, for instance), there are sensitive electronic control loops
and motors that can adjust the gap according to operational requirements.
Air / fuel gas mixture
Ratio
Precautions
HON 985A-100/50-ZW-N-NI
Constriction
device (torpedo)
Gas 1
(Air)
Venturi nozzle
Adjustable
mixing gap
Mixing zone
Fig 1: Functional principle
985.29-2 p.04
not rich enough
increase the mixing gap
Gas 2
(Fuel gas)
too rich
reduce the mixing gap
Stepper motor
with control*
Air / fuel
gas mixture
*) Stepper motor control, e.g. for
– λ-control
– Control of cylinder temperature
– Electronic spark control